X-ray photoelectron spectroscopy (XPS) has become increasingly important over the past few years for supporting the development of ultra-thin layers for high-k metal gates. As the analysis depth of XPS is however limited to about 5-7 nm, it would be extremely useful if the analysis could be carried out from the backside using standard silicon wafers. This approach puts extreme requirements on the sample preparation as hundreds of micrometers of bulk silicon have to be removed and one has to stop with nanometer precision when reaching the interface to the ultra-thin layer stack. Therefore, we have developed dedicated procedures for preparing and analyzing samples for backside XPS analysis. This paper presents the developed approach with a focus on sample preparation using plan-parallel polishing, endpoint detection by interference fringes, and selective wet etching. First angle-resolved XPS (ARXPS) analysis results of metal gate stacks demonstrate the power of such backside analysis.

For the material (Pb0.95Sn0.05Te)1-x(PbS)x nanostructuring from nucleation and growth and spinodal decomposition were reported to enhance the thermoelectric figure of merit over bulk PbTe, producing ZT of 1.1 - 1.4 at 650 K for x = 0.08[1]. Thermoelectric modules made from (Pb0.95Sn0.05Te)1-x(PbS)x materials with various hot-side metal electrodes were fabricated and tested. Short circuit current was measured on unicouples of Pb0.95Sn0.05Te – PbS 8% (n-type) legs and Ag0.9Pb9Sn9Sb0.6Te20 (p-type) legs over 10 (A) for a hot side temperature of 870K, and a cold side of 300K. Hot pressed (Pb0.95Sn0.05Te)1-x(PbS)x materials were also investigated for module fabrication. Investigations of the electrical properties of hot-pressed (Pb0.95Sn0.05Te)1-x(PbS)x materials are presented along with the latest advancements in the fabrication and characteristics of modules based on the processing of these materials.

Vertically aligned carbon nanotubes (VACNTs) grown on bulk copper substrate are of great importance for CNT real-life applications as thermal interface materials in microelectronic packaging. However, their reproducible synthesis has been a great challenge so far. In this study, by introducing a well-controlled conformal Al2O3 support layer on the bulk copper substrate by atomic layer deposition (ALD) prior to the deposition of the iron catalyst layer, we reproducibly synthesize VACNTs of good alignment and high quality on the copper substrate, using a conventional thermal chemical vapor deposition process. The alignment and the quality are characterized by scanning electronic microscopy and Raman spectroscopy, respectively. The roles of the conformal Al2O3 support layer are discussed. A kinetics-controlled growth mechanism is shown. This progress provides a viable VACNT commercial application for thermal management, on the basis of which, we show a recent progress on a state-of-art Si/VACNT/Cu assembling process, named “chemical anchoring”. The high quality of the VACNTs on the copper growth substrate and the covalent bonding formed between the VACNTs and the silicon mating substrate greatly reduces the thermal resistance of the VACNT-mediated thermal interface.

The objective of this study was to experimentally measure the properties and performance of a series of glasses with compositions that could represent high level waste Sludge Batch 5 (SB5) as vitrified at the Savannah River Site Defense Waste Processing Facility. These data were used to guide frit optimization efforts as the SB5 composition was finalized. Glass compositions for this study were developed by combining a series of SB5 composition projections with a group of candidate frits. The study glasses were fabricated using depleted uranium and their chemical compositions, crystalline contents and chemical durabilities were characterized. Trevorite was the only crystalline phase that was identified in a few of the study glasses after slow cooling, and is not of concern as spinels have been shown to have little impact on the durability of high level waste glasses. Chemical durability was quantified using the Product Consistency Test (PCT). All of the glasses had very acceptable durability performance. The results of this study indicate that a frit composition can be identified that will provide a processable and durable glass when combined with SB5.

A technique combining both atomic force microscopy (AFM) and scanning electron microscopy (SEM) is used to evaluate the mechanical properties of individual collagen fibrils from the fractured surface of antler. SEM is used to locate individual mineralized collagen fibrils and allow visualization of the attachment of these fibrils to the end of an AFM probe. Tensile testing of individual collagen fibril to failure was performed using the AFM with resultant stress-strain curves obtained. Tensile strengths of up to 0.18GPa are found for some individual collagen fibrils, indicating the presence of mineral in improving mechanical performance. Consideration of the SEM operating parameters indicates that the amount of time the sample is within the SEM vacuum can affect the resultant mechanical behavior of individual fibrils.

Hole drift mobilities in hydrogenated amorphous silicon (a-Si:H) and nanocrystalline silicon (nc-Si:H) are in the range of 10-3 to 1 cm2/Vs at room-temperature. These low drift mobilities establish corresponding hole mobility limits to the power generation and useful thicknesses of the solar cells. The properties of as-deposited a-Si:H nip solar cells are close to their hole mobility limit, but the corresponding limit has not been examined for nc-Si:H solar cells. We explore the predictions for nc-Si:H solar cells based on parameters and values estimated from hole drift-mobility and related measurements. The indicate that the hole mobility limit for nc-Si:H cells corresponds to an optimum intrinsic-layer thickness of 2-3 μm, whereas the best nc-Si:H solar cells (10% conversion efficiency) have thicknesses around 2 μm.

Initiation of pathways that lead to proliferation and chemoresistance by Toll-like receptors (TLRs) is an important factor in cancer progression. Here, we show the response of human cancer cells to TLR signaling inevitably linked to tumor biology. The approach is based on tailored multifunctional magnetic nanoparticles equipped with pathogen-derived ligands (CpG) functioning as TLR agonists (molecular component) to investigate the impact of transcription factor immune activation on human cancer cells. Magnetic nanoparticles (MnO and bifunctional Au-MnO) particles were covalently coated with a multifunctional polymer, displaying no cytotoxicity, to being able to enter cells while carrying foreign DNA (unmethylated CpG) to recognize intracellular TLR 9. Both, the particle and the nucleic acid are tagged with fluorescent markers for simultaneous visualization inside the cell. Apart from optical imaging, the magnetism of the particles also allows magnetic resonance imaging of organisms.

Three different classes of boron and nitrogen containing light metal complex hydrides have been investigated, resulting from the reactions of LiNH2 with LiBH4, NaNH2 with NaBH4 and MHx (where M = Li, Na and Ca) with NH3BH3. A rich variety of new phases has been identified, which exhibit modified decomposition pathways and onset temperatures of hydrogen desorption as low as 40°C. In each case the composition of phases formed has been examined in detail and the products of thermal decomposition—solid and gaseous—have been determined.

The figure of merit ZT = sS2T/k (S the Seebeck coefficient, s and k the electrical and thermal conductivity respectively) is an essential element of the efficiency of a thermoelectric material for applications which convert heat to electricity or, conversely, electric current to cooling. From the expression of the power factor sS2 it was deduced that a highly degenerated semiconductor is necessary. In order to reduce the lattice part of the thermal conductivity, various mechanisms were tested in new thermoelectric materials and those had been the topics of several reviews. These include cage-like materials, effects of vacancies, solid solutions, complex structures (cluster, tunnel, …,), micro- and nano-structured systems, and more recently semiconducting glasses. We plan to review such aspects in the modern thermoelectric materials and include results of the very last years. Moreover, as micro- and nano-composites seem to be promising to increase ZT in large size samples, we will also briefly discuss the interest of spark plasma sintering technique to preserve the micro- or nano- structure in highly densified samples.

Linear and non-linear optical properties of conjugated polymers are often masked by the inter-chain network in solid state. The formation of aggregates may trap excitons, reduce oscillator strength and modify relaxation processes. The control of the inter-chain interaction is the main reason for developing “threaded” polymers, where supra-molecular encapsulation should reduce aggregation. Here, we investigate the influence of the encapsulation with β-cyclodextrin (β-CD) macrocycles on the photophysics of the polyfluorene-alt-biphenylene (PFBP) using femtosecond non-linear spectroscopy. Upon threading we observe enhancement of the stimulated emission (SE) in the visible range and reduction of the charge absorption. These phenomena are ascribed to the reduced inter-chain interaction. In more isolated chains the dynamics of intra and inter-chain charge states are distinguished. In addition, we performed three-beam experiments in which a first pulse (pump) creates singlet excited states; a second (push) pulse re-excite the singlet state and a broadband probe pulse detects the induced changes in transmission. This technique shows: (i) charges are generated from higher lying singlet states also in isolated chains (ii) ultrafast optical gain switching is possible in threaded chain.Finally, we demonstrate that ASE occurs in films of threaded polymers and lasing can be achieved with much lower threshold than the neat polymer chain in the DFB configuration. All our findings point out the potential role of rotaxanes in photonics, as amplifiers and reopen the route to the electrically pumped organic lasers and all-optical logic devices.

From an evolutionary viewpoint, the molluscan nacre constitutes a fascinating object. This microstructure appeared early, in the Lower Cambrian period, about 530 million years ago, and since then, has been kept unchanged until today. Nacre is restricted to the conchiferan mollusks, where it occurs in t least three main classes, bivalves, gastropods and cephalopods. The aim of the present study is to investigate whether all nacres are built from the same “macromolecular tools”, proteins of the nacre matrix. To this end, we studied three new nacre models, the freshwater bivalve Unio pictorum, the cephalopod Nautilus macromphalus, and the gastropod Haliotis asinina, to which we applied a combined biochemical and proteomic characterization of their respective nacre matrices. The results of our approach, that can be defined as “shellomics” (proteomics applied to shell proteins) shed a new light on the macroevolution of nacre matrix proteins and on the in vitro design of nacre-like biomaterials.

GeTe-Sb2Te3 pseudobinary compounds are attracting considerable attention as phase change materials for optical disk and phase change random access memory (PRAM). In these compounds, Ge2Sb2Te5 (GST) has been used for an optical disk memory such as DVD-RAM because the crystallization by laser beam heating is very fast (∼20ns). Recently, the GST has been much considered as material for PRAM and, therefore, the electrical resistance change due to crystallization and the phase change by applying an electrical current have been widely investigated. On the other hand, although GeTe compound has been suggested as the phase change material for the optical disk by Chen et al in 1986, the study focusing on the phase change material for PRAM is limited. Since GeTe is known to show the phenomenon of electrical switching, this compound has a potential of PRAM. In this study, the electrical resistance and crystalline structural changes on crystallization process in Ge-Te thin films were investigated.

Films of amorphous Ge100–xTex (x : 46-94) with 200 nm thickness were deposited by sputtering of GeTe alloy target or co-sputtering of GeTe and Te targets on SiO2/Si substrates. In-situ electrical resistance measurements during heating process of these films were performed by two point probe method in a heating rate of 2∼50°C/min. X-ray diffraction (XRD) analysis was employed for the structural identification of thin films for 10-60° in 2′ using X-ray diffractometer with Cu-K. Transmission electron microscope (TEM) analysis was carried out to investigate the microstructure and to identify crystalline structure. The compositions of these films were confirmed by energy dispersive X-ray spectroscopy (EDS) attached TEM.

All as-deposited Ge-Te films were confirmed amorphous by XRD and TEM. From the in-situ electrical resistance measurements, it is found that resistance change with crystallization process depends on the composition and the stoichiometric GeTe compound shows abrupt electrical resistance change at around 190 °C. The crystallization temperature of GeTe was higher than that of GST and resistance difference between the amorphous and the crystal was also larger. While the electrical resistance of GST film gradually decreased with increasing temperature after the crystallization at around 160 °C, that of GeTe film showed small temperature dependence after crystallization. It was found by X-ray measurement observation that the amorphous GeTe compound film crystallized first into a cubic state, and then into a stable rhombohedral state by further heating. The crystallization kinetics of Ge-Te thin films will be also presented.

Recent research indicates that nanophysical properties as well as biochemical cues can influence cellular re-colonization of a tissue scaffold. It has also been shown nanoscale elasticity can strongly influence cellular responses. In the present work, quantitative investigations of the elasticity of a nanofibrillar matrix scaffold that has demonstrated promise for spinal cord injury repair are compared with complementary transmission electron microscopy investigations, performed to assess nanofiber internal structures. Interpretive model improvements are identified and discussed.

Lab-on-a-chip (LOC) is one of the most important microsystem applications with promise for use in microanalysis, drug development, diagnosis of illness and diseases etc. LOC typically consists of two main components: microfluidics and sensors. Integration of microfluidics and sensors on a single chip can greatly enhance the efficiency of biochemical reactions and the sensitivity of detection, increase the reaction/detection speed, and reduce the potential cross-contamination, fabrication time and cost etc. However, the mechanisms generally used for microfluidics and sensors are different, making the integration of the two main components complicated and increases the cost of the systems. A lab-on-a-chip system based on a single surface acoustic wave (SAW) actuation mechanism is proposed. SAW devices were fabricated on nanocrystalline ZnO thin films deposited on Si substrates using sputtering. Coupling of acoustic waves into a liquid induces acoustic streaming and motion of droplets. A streaming velocity up to ˜5cm/s and droplet pumping speeds of ˜1cm/s were obtained. It was also found that a higher order mode wave, the Sezawa wave is more effective in streaming and transportation of microdroplets. The ZnO SAW sensor has been used for prostate antigen/antibody biorecognition systems, demonstrated the feasibility of using a single actuation mechanism for lab-on-a-chip applications.

Nanoelectromechanical systems (NEMS) based on nanomaterials, especially NEMS resonators made of suspended nanowires, nanotubes or nanosheets have emerged as promising devices for many sensing applications. However, operation of such NEMS resonators in liquids is usually difficult due to strong viscous damping. Here we present our progress in developing NEMS devices based on suspended nanomaterials that can operate in liquids. We present our measurements performed on suspended metallic nanowires driven by AC currents in a magnetic field in liquids.

Tailoring of properties and functions of shape-memory polymer networks to the requirements of specific applications demands a knowledge-based approach. A comprehensive database enabling the analysis of structure-property relationships is obtained by the systematic variation of molecular parameters. In detail we investigated the influence of the nature of thermal transition on the shape-memory behavior of polymer networks. Furthermore, additional amorphous phases were introduced enabling tailoring of elastic properties especially in the temporary shape as a consequence of the formed polymer morphology. Enabling higher elasticity, adjustable hydrolytic degradability, and the possibility to tailor the transition temperature of shape-memory to a temperature between room temperature and body temperature are considered to be substantial steps to improve the applicability of these active polymers in medicine.

With respect to Silicon-on-Diamond approaches as an alternative to SOI where diamond is used as the buried dielectric, we have in recent works demonstrated the feasibility of a novel approaches where the CVD diamond layer is grown on silicon using Bias Enhanced Nucleation (BEN) over large area substrates, then smoothed and assembled to successfully enable the fabrication of first prototypes of silicon-on-diamond substrates. The key novelty to those SOD substrates were that only a very thin box dielectric diamond layer is used (typically from 150 to 500nm thick), as required by the current SOI technology. However we had also observed that the silicon-diamond interface quality to be sensitive to the nature of the nucleation interface. Thus the current contribution here studies the chemical nature of various capping materials used to solve the issue of electrical defects in case of direct silicon-diamond interface and at the same time to enable the whole system to benefit from the high thermal conductivity of diamond when compared to other standard electrical insulating materials.

For light emitting diodes (LEDs) to be used for general lighting, high efficiencies would need to be retained at high injection levels to meet the intensity and efficiency requirements. In this regard, it is imperative to overcome the observed drop in LED efficiency at high injection levels beyond that would be expected from junction temperature. The suggested genesis of efficiency degradation includes electron overflow or spillover, also suggested to be aided by polarization induced electric field, Auger recombination, current crowding, and elevated junction temperature. Setting the junction temperature aside, the degree to which or even whether each of these mechanisms plays a role is still under debate. We have undertaken a series of experiments to isolate, whenever possible, the aforementioned processes in an effort to determine the causes of efficiency loss at high injection levels. By using 1μs pulsed electrical injection with 0.1% duty cycle, we were able to minimize the effect of the junction temperature. By changing the design of the multiple quantum well region as well as by employing or not employing electron blocking layers, we demonstrated the important role that electron overflow plays on efficiency. Furthermore, by also exploring the same on non polar surfaces and observing any lack of dispersion in terms of the effect of the electron blocking layer we can conclude that the polarization induced field does not seem to play a major role. LEDs on non polar surface with no notable efficiency degradation, up to current densities of about 2250 Acm-2 used for measurements, have been obtained which seems to imply that Auger recombination up to these injection levels is not of major importance, at least in the structures investigated. The effect of current crowding on efficiency droop was investigated by comparing semitransparent Ni/Au p-contacts and transparent conducting oxide contacts (Ga-doped ZnO). Because the latter showed notably reduced efficiency degradation at high injection levels, we can conclude that current crowding plays a role as well.

Production of biodiesel fuel (fatty acid methyl ester) by use of conventional method (alkaline catalyst method) requires deacidification process prior to the reaction and refining process to remove the catalyst after the reaction. These processes increase total cost required for production of biodiesel fuel. In order to solve the problem, authors recently proposed a method called superheated methanol vapor method. In a process with this method, superheated methanol vapor is continuously bubbled into the oil in the reactor vessel and reacted with triglycerides to form fatty acid methyl ester and glycerol. The fatty acid methyl ester and glycerol formed flows out of the reactor together with unreacted methanol vapor and is collected using a condenser. Reaction using the superheated methanol vapor method can be conducted at atmospheric pressure. Production of fatty acid methyl ester by use of the superheated methanol vapor method does not require refining process after the reaction because no catalyst is used in this method and fatty acid methyl ester can be separated from glycerol simply by sedimentation. The method does not require deacidification process prior to the reaction because not only triglyceride but also free fatty acid can be converted into fatty acid methyl ester by use of the method. Therefore, both initial and running costs required for biodiesel production are thought to be reduced by applying the method. In order to estimate the cost required by a process based on the superheated methanol vapor method, a demonstration plant (design productivity: 400 L/d) was constructed and its efficiency was evaluated. The plant could produce 425 L of fatty acid methyl ester in a day from used frying oil. Energy consumed in each unit of the demonstration plant was measured (electrical energy and thermal energy). Based on the energy consumption data obtained with the demonstration plant, production cost required with a practical scale plant (designed productivity: 6000 kL/y) was calculated. The cost required by the practical scale plant with the superheated methanol vapor method was estimated to be 40.2 yen/L (about 40 cent/L) while the cost required by a plant with the alkaline catalyst method was 62.5 yen/L (about 62 cent/L). The estimated cost includes depreciation cost, cost of repairing, labor cost, methanol cost and energy cost (heat and electricity). Most of the energy consumed by the plant was thermal energy and the plant could be automatically controlled. Therefore, required cost will be further decreased by installing the plant next to an incineration facility because thermal energy can be supplied from the facility and the labor cost can also be supported by the facility.

LiFePO4/C composite cathode materials were synthesized by one-step solid-state reaction using FePO4 as main raw materials and solid PVA (Polyvinyl Alcohol) as a reductive agent and carbon source. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis and charge-discharge test. The results indicated that the carbon generated from the pyrogenation of PVA did not affect the olivine structure of the cathode materials but considerably improved its high-rate discharge ability and cycle performance. The initial discharge capacity of the sample was 149.7, 133.1, 120.6, 93.0 mAh/g at 0.2C, 1C, 2C, 5C respectively, and the discharge capacity could reach 90 mAh/g at 5C rates after 80 cycles. It is believed that the carbon coating could lead to small particle size and high electronic conductivity of active materials, thus leading to excellent electrochemical performance of LiFePO4/C cathode materials.